1. Field of the Invention
This invention involves a needle guide mount for attachment to an ultrasound probe.
2. Description of the Related Art
Many surgical procedures involve inserting a needle or cannula into a patient while viewing an image of the region of insertion. These include such procedures as needle biopsy, drainage, amniocentesis, precision injections, cell aspiration, and radio-frequency cauterization. For example, ultrasonic imaging is often used to guide the insertion of a biopsy needle in order to more accurately obtain a tissue sample from a region of interest. Such image-aided needle insertion may also be helpful when one wants to inject or extract a fluid into or from a precisely defined place within the patient.
During these procedures, an ultrasonic probe is held against the patient's body, usually along with some coupling agent. An image of the area of the body adjacent to or near the probe is then created and displayed using conventional ultrasonic imaging techniques while the physician inserts the needle and guides it towards its target. At least portions of both the needle and the target are visible on the display.
Often, the physician mounts a needle guide on the transducer probe while continuing to watch the display screen--looking away from the screen might cause him to move the probe and thus lose the image of the target. He then assumes that the needle, once inserted, will follow a course along or between one or more guide lines that are displayed on the display screen.
Many needle guides, however, can mount onto the probes with different orientations. For example, if the probe has a circular cross section and the needle guide has a circular clamp-like mounting arrangement, then the needle guide could end up with an angular position far from the proper position. Even probes with non-circular cross-sections can have two or more "secure" mounting positions, only one of which will be correct. For example, a probe with a substantially rectangular cross-section might allow mounting of a needle guide on either of the two short sides. If the physician, while watching the display screen, accidentally mounts the needle guide with an incorrect orientation and then inserts the needle, then the needle will penetrate the wrong part of the patient's body. The disadvantages of such a potentially grave error should be obvious to even the most stoic who imagine themselves the hapless, cringing recipients of such an incorrect needle insertion.
Conventional arrangements all fail either to clamp the needle guide to the probe securely, or to do so in a such a way as to eliminate the risk that the guide will be mounted with the wrong orientation. What is needed is a needle guide that can be both securely mounted on a probe only when it provides the correct needle orientation.